nwsc_proxy: support creating Support Profile with "status": "existing"

[mackenzie-grimes-noaa]

Linear Issue

IDSSE-1038

Changes

• Add idss-engine-commons library dependency
  • Only needed for to_iso()
• Add support for nwsc_proxy webserver POST endpoint so client can control the status of their Support Profile
  • Previously all Support Profiles were created in the "new" category, only to be returned when someone requested /all-events?status=new

Explanation

Now POSTs to /all-events must have a slightly different request body.

Previous

{ 
  // <...full Support Profile JSON> 
}

Now:

{ 
  "status": "existing",  // or "status": "new"
  "data": { 
     // <...full Support Profile JSON> 
  } 
}

[Geary-Layne]

LGTM